微量蛋白質的偵測，在蛋白質體學研究中是非常具挑戰的主題。利用化學法修飾生物分子的帶電性，進而提升質譜訊號的靈敏度，則是目前具有潛力的解決方法之ㄧ。其中以胍基衍生物來修飾的胜肽，則是最值得注意的。然而其化學修飾物之官能基與訊號強度之間的關係並未探討。本論文將利用開發出新的環化合成方法，來製備出具推電子基、五環、六環、氫氧基及掌性異構之不同功能性之試劑，再與胜肽中離胺酸耦合成一系列的胍基衍生物，經由NMR 鑑定，高效能液相層析儀分析，及LC-MS/MS 確認這些胍基衍生物的形成。利用基質輔助雷射脫附游離質譜，將胰蛋白酶水解之肌紅蛋白中的ㄧ段胜肽與化學試劑耦合之結構與訊號強度之間的探討。經比對結果顯示，六環結構於質譜訊號強化15.1 倍、五環強化9.2 倍、推電子基強化12.3 倍、氫氧基強化7.6 倍與掌性異構強化12.3-12.4 倍。此結果顯示出，電荷的穩定性對訊號靈敏度的提升，具有決定性的影響，對後續研發ICAT 與iTRAQ 等蛋白質定量試劑具有相當重要的指標意義。 Detection of low abundant proteins is one of challenging topics in proteomics. Guanidino group was demonstrated to enhance the signal instensity in MALDI experiments. This report described a novel synthetic pathway to prepare the cyclic guanidino derivatives. The guanidino moiety was generated by O-ethylisourea and amino group of lysine-specific side chain. The characterization and identification was performed by NMR, HPLC, LC-MS/MS and MALDI. The result suggested the stabilization of positive charge at guanidino group plays an important role in signal enhancement of mass spectra of proteins. These results provide a further application in the ICAT and iTRAQ for protein quantification.
